The understanding of the physiological functions of the human erythrocyte carbonic anhydrase depends on the complete characterization of their enzymatic catalysis and inhibition. This study aims at completing the kinetic description of their carbon dioxide hydration-dehydration activities, using stop-flow kinetic techniques, and at providing a molecular description of the role of active-site groups in the catalysis and inhibition. Chemical modification and spectroscopic (U.V. and H1 and C13 nuclear magnetic resonance) methods are used to complement the kinetic approach.